minerals Article Successful Ecological Regeneration of Opencast Coal Mine Spoils through Forestation: From Cradle to Grove Martin Haigh 1,2,* , Patricia Woodruffe 1, Margaret D’Aucourt 1, Elanor Alun 3, Gillian Wilding 1, Susan Fitzpatrick 1, Ekaterina Filcheva 4 and Maya Noustorova 5 1 Cradle for Nature (NGO), cradlefornature.org, Witney OX29 8HT, UK; [email protected] (P.W.); [email protected] (M.D.); [email protected] (G.W.); susan@fitzpatrick7.plus.com (S.F.) 2 Department of Social Sciences, Oxford Brookes University, Oxford OX3 0BP, UK 3 School of Architecture, Built and Natural Environments, University of Wales Trinity St David’s, Swansea SA1 8EW, UK; [email protected] 4 Institute of Soil Science, Agrotechnology and Plant Protection “N. Poushkarov-Sofia”, 1080 Sofia, Bulgaria; fi[email protected] 5 Department of Soil Science, University of Forestry, 1797 Sofia, Bulgaria; [email protected] * Correspondence: [email protected] Received: 15 April 2020; Accepted: 15 May 2020; Published: 20 May 2020 Abstract: The reclamation of surface (opencast) coal mines is not always successful; there remains a legacy of degraded land that burdens local communities. This article evaluates a community-oriented, low-cost means of geoecological regeneration, the “Cradle for Nature” strategy, which uses mosaic tree planting to foster positive natural ecological processes. Results show that, while the autocompaction of minestones quickly raises soil densities to levels hostile to plant growth, forestation helps moderate soil densities. Weathering concentrates metals in minestones, but 14 years of forestation reduced the loadings of five metals by 35–52%. Twenty years of forestation doubled soil organic carbon to >7%; increased bacilli from 7% to 46%; actinomycetes from 10% to 26%; and soil microbe counts 12–15 times, especially in tree plantings treated with fertiliser. Soils under trees also supported a significantly greater earthworm biomass than under grass but, while open-canopy plantings had increased ground flora biodiversity, closed-canopy plantings had lower diversity and biomass. Following closure to grazing, ground biomass increased sevenfold. Young trees act as bird perches and significantly increase seed fall. Small mammal biomass and biodiversity increases after tree planting and higher predators appear. Varteg’s constructed forest provides an effective “cradle” for an emergent geoecological system and its habitat mosaic maximises biodiversity. Keywords: land reclamation; opencast/surface coal mining; ecological regeneration; South Wales Coalfield; Cradle for Nature 1. Introduction Surface mining consumes land; land reclamation is the process of returning mined-through land to an environmentally and socially acceptable state. Unfortunately, as in the recycling of other industrial wastes, the recycling of surface-mined land can prove difficult. The reality of much land reclamation work falls far short of its initial promise and environmental reconstruction owes as much to faith as to science [1]. Even today, while land reclamation successes are showcased, its shortfalls and failures are ignored. Despite the routine assurances offered by those who propose new mines, the land left behind by surface coal mining tells its own story and it is clear that no one is able to guarantee its quality. All too often mining communities are left with a legacy of unreclaimed, poorly reclaimed, actively Minerals 2020, 10, 461; doi:10.3390/min10050461 www.mdpi.com/journal/minerals Minerals 2020, 10, 461 2 of 27 degrading, or otherwise substandard “reclaimed land”. The fact is that, while the money generated by surface mining disappears quickly, its legacy remains for the very long term and often creates a burden for affected communities that, typically, they have neither the funding nor the technical resources to address. This paper evaluates the long-term results of an attempt to design an effective low-cost, low-tech, community-based remedy for degraded and degrading “reclaimed” land and “orphan” surface mine spoil dumps. The approach is based on a strategy of selective tree planting to encourage the regeneration of more natural woodland and the restoration of soil fertility in land degraded by mining. Called the “Cradle for Nature” strategy [2], tree planting is used to reverse ongoing geoecological decline and to create a “Cradle for Nature”, namely new habitats that can be colonised by local species, so fostering positive geoecological successional development. This contribution describes the ecological changes associated with tree planting on this project’s test plots on the former opencast coal mine site at Varteg, South Wales, which is close to UNESCO’s “Industrial Landscape World Heritage site” at Blaenavon. It evaluates current knowledge concerning the physical and chemical amelioration of soils, the development of soil microbial and earthworm ecology, changes in plant and animal ecology, and the role of birds in promoting seed fall and plant colonization. 1.1. The “Cradle for Nature” Strategy Land reclamation projects reflect their designers’ state of mind. If a reclamation begins to fail, usually this is because of the way the project was imagined and implemented as much as due to any natural process. Society decides both the timescales and the responsibilities of mining agencies and the balance struck between the miners’ profits, the law, national needs, and the present or the future needs of society and/or the environment. It also decides the status of land reclamation and whether this is considered integral to mining or an (optional) “after thought” and whether it is conceived as a single action or an ongoing process. Certainly, in today’s legislative environments, it is becoming more difficult for miners to walk away from the aftermath of their mining, especially where the landscape includes so much. Those responsible for unreclaimed or poor quality “reclaimed” land, increasingly, are named, shamed, and used as evidence against their industry and in support of arguments against granting planning permits for further opencast mining, as finally realised, nationally, in Wales in 2018 [3–5]. Nevertheless, field inspection of past reclamation projects suggests the existence of three psychologies of opencast mine reclamation. First is “cosmetic” reclamation, which is designed only to pass legal inspection requirements at the end of a set period of aftercare. Second is economically sustainable reclamation, where the site is designed for a new economic use that can fund foreseeable future maintenance costs. Third is environmentally self-sustainable reclamation, where the land is restored to a condition where nature can take control and maintain the quality of the land, which is especially useful where no high value after uses are apparent. This style of reclamation, by restoring ecological functioning, allows natural processes to rebuild the land’s environmental quality. This is the land reclamation of forestry, ecology, amenity, and green spaces and its key word is “self-sustaining”, which is something only nature can provide [6]. Here, this project’s “Cradle for Nature” strategy involves creating, through tree planting, “forest fallowing”: new habitat conditions that foster the development of a natural ecosystem. The expectation is that, in time, this new ecosystem will supersede the artificial plantings that were needed, initially, to reverse previous environmental decline. The “Cradle for Nature” trees are planted as temporary biomass accumulators designed to improve local habitat conditions and nurture the development of the depleted geoecological system toward autonomous self-sustainability [2]. This paper describes the evidence to date that system restoration is beginning to take effect. 1.2. Test Site Location and Description The Varteg test sites are located between 360 and 370 metres above mean sea level on the western outcrop of the South Wales Coalfield in Torfaen County Borough. The site is part of an artificial Minerals 2020, 10, x FOR PEER REVIEW 3 of 28 1.2. Test Site Location and Description MineralsThe2020 Varteg, 10, 461 test sites are located between 360 and 370 metres above mean sea level on3 ofthe 27 westernMinerals outcrop 2020, 10 of, x FORthe PEER South REVIEW Wales Coalfield in Torfaen County Borough. The site is part3 of 28of an artificial terrace created in 1963 during the reclamation of the Varteg Hill (Waun Hoscyn Extension) 1.2. Test Site Location and Description Opencastterrace created Mine in(51°44 1963′ during50–53” theN 03°07 reclamation′72–98” ofW; the Figure Varteg 1). Hill This (Waun south-east-facing Hoscyn Extension) slope Opencast on the westernMine (51 flank◦The44050–53” Vartegof Cwm Ntest 03Afon sites◦07 0Llywd 72–98”are located is W; both Figure between relative1). This360ly andwarm south-east-facing 370 and metres exposed above slope tomean the on theprevailingsea westernlevel on westerly flankthe of winds.Cwmwestern AfonIts mean Llywdoutcrop monthly is of both the air relativelySouth temper Walesatures warm Coalfield range and exposedin from Torfaen 2.5 to toCounty the 15 prevailing °C. Borough. Its average westerly The siterainfall is winds. part (1971–2000) of Its an mean artificial terrace created in 1963 during the reclamation of the Varteg Hill (Waun Hoscyn Extension) wasmonthly 1543 airmm/year. temperatures Evaporation range fromis estimated 2.5 to 15 as◦C. 472 Its mm/year average rainfallon rough (1971–2000) grazing land. was 1543Natural mm soils/year. EvaporationOpencast is Mine estimated